Chapter 7 Synthesis
This section synthesizes the information generated through the mapping exercise and the discussions which were had when presenting the results of this project.
7.1 General conclusions
This modelling exercise has demonstrated that we cannot take for granted that the existing protected area network is resilient to future climate change. One of the fundamental assumptions prevalent in the current literature is that species ranges will shift to accommodate climate changed related alterations in thermal and moisture niches - typically moving up mountainsides to reach cooler, wetter locations. However, the majority of the parks assessed here showed substantial hurdles in the capacity for wildlife to respond to such changes. High elevation areas (>1500m) are typically cutoff from their low elevation counterparts by substantial anthropogenic disturbance and unprotected habitats. This, however, is not always the case, several “gold standard” climate corridors exist which are 100% protect with good quality forest (notably in Panama), but these are the exception not the rule.
7.1.1 Country comparisons
Given the findings of the least cost paths section, we find clear differences in the degree to which lowland protected areas are connected to high elevation projected areas. We believe these differences directly relate to how resilient protected areas are to future climate change. Of the countries assessed, Panama contains the most connected climate corridors, largely due to the size and scale of the Darien Protected area. Costa Rica follows Panama, principally due to the importance of La Amistad protected area, a park where the climate corridors connect for 25 different lowland protected areas. The quality of putative climate corridors in El Salvador were very low, largely due to the high degree of human modification in this region. Whilst other countries fell between the two extremes.
7.2 Important high elevation areas
Circuitscape modelling revealed that La Amistad is a crucial high elevation end point for many of the putative climate corridors. This is likely owing to it being large, contiguous, and one of only a few options in Costa Rica and Panama. Other important areas include the complex of smaller high elevation protected areas in western Honduras (including Opalaca, El Jilguero and Celaque), and the larger Sierra de las Minas and Cuenca del Largo Atitlan in Guatamala. Robust management and expansion of these locations may be key to having a resilient protected areas system in the future.
7.3 Priority climate corridors
We used a least-cost-paths approach to highlight ten broad geographic regions which would be beneficial targets for restoration of ridge to reef connectivity. These regions were spread throughout central American countries, however it was notable that there were non-selected in El Salvador, as the protected areas there are typically small and nested within a highly disturbed landscape. Circuitscape models revealed the variety of challenges facing restoration initiatives looking to connect lowland and highland habitats: lowland protected areas are typically surrounded by high degrees of human modification and poor quality (low biomass) forest. The three most promising locations for restoration, of the ten assessed, appear to be Osa Peninsula, Rio Platano and Indio Maiz - as they involve large lowland protected areas connecting to large upland areas across manageable distances.
7.4 Unprotected high elevation (>1500m) habitat?
In this exercise we only consider protected high elevation habitats. However, there is the potential for non-protected high elevation habitats to contribute to climate corridors. The plot below highlights the unprotected high elevation (>1500m) forests (>25 Mg C ha−1).
We estimate that (1.26406^{4}) km2 of high elevation (>1500m) forests are protected. However, substantial tracts of important forest remain unprotected (1.74358^{4}) km2, the vast majority of such forests lie in Guatemala and Honduras. There appears to be limited potential for high elevation protected area expansion outside of these counties, although some expansions may be possible around La Amistad (Costa Rica and Panama).
7.5 Existing corridors
Given that we have identified putative climate corridors, it follows that we should ask if these corridors are already covered by existing/proposed corridors. Below we explore the overlay of the Mesoamerican Biological Corridors (MBCs) with those identified in this mapping exercise.